import java.util.HashSet;
import java.util.UUID;

public class ALandHSM {
    public static void main(String[] args) {
        System.out.println("hello");
        HashSet<String> set = new HashSet<>();
        new Thread(new Runnable() {
            @Override
            public void run() {
                for (int i = 0; i < 100; i++) {
                    set.add(UUID.randomUUID().toString().substring(0, 8));

                    System.out.println(set);
                }
            }
        }).start();
    }
}
